Apparatus and method for molding tubes from cementitious material



Oct. 2, 1951 SALVANESCHI APPARATUS AND METHOD FOR MOLDING TUBES FROM CEMENTITIOUS MATERIAL 5 Sheets-Sheet l Filed July 20, 1949 IIIIIIIIIIII S of APPARATUS AND METHOD FOR MOLDING TUBES FROM CEMENTITIOUS MATERIAL Oct. 2, 1951 P. sALvANEscHl 2,569,538

Filed July 20, 1949 5 Sheets-Sheet 2 g 11 E s; La..

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Oct. 2, 1951 P. sALvANEscl-n 2,569,538

APPARATUS AND METHOD FOR MOLDING TUBES FROM CEMENTITIOUS MATERIAL Filed July 20, 1949 5 SheevlZS-Sheet 3 F/54. F/E

m e2 du@ ,46E/VTS Patented Oct. 2, 1.951

APPARATUS'. AND METHOD FOR NIOLDING:y TUBES FROM CEMENTITIOU'S MATERIAL Pino Salvaneschi, Mexico City, Mexicovv Application July 20', 1949, Serial No..105,704 In Italy August 21,1948

19'. Claims: 1`

Processes are known forV the manufacture of tubes of fibrous cement produced: by1 wrapping preeformed layers of' Vpaste and applyingthem successively'round a rotatable core.

OtherA processes are also known by which the tubes are constructed between pairs of" rotating cylinders. Known likewise isV the processv by which the tubes are produced by suitably pouring the paste on :a shaking' table acting against a porous mandrel. f

A new process has now'been found which permits of obtaining with trulyY remarkable rapidity and 'by' much more simple means frompastes capable of hardening, tubes and generally hollow solids of revolution, which may be of diierent thicknesses and various diameters along'one and the same generatrix. 'Ihe` advantagesy which Acharacterise this new process are theI following:

Simplicity of` means for carrying itout.

Possibility of obtaining if notl completely automatic operation, at any'rate semi-automaticproduction. y

Rapidily'of production; inasmuch as it has already been experimentally determined thatA for certain diameters and thicknesses the tota-lV time of' manufacture and compression-maybe reduced eventoSOseconds.

Possibility of using up thewhole ofthepaste withoutwaste.

Possibility 4of: obtaining thicknesses within veryv limitedtoleranc'es.

Excellent' external nish" and excellent qualities' of'strength.

The possibilityof" producting tubes, the inter nal parts of which are specially suited 'for resisting the strains of hydrostatic ypressure and the external. parts of which are of veryv cheap material; l

l Possiblity off obtaining tubes from `cement pactes. with very few libres and.' even without iibres.

` Possibility of producing reinforced. tubes with cage, spiral` and double 1. spiral .armouring, thereinforcement being. embodied in the tube, during its formation.

Possibility of. centering such reinforcement without supporting it. The new process. -is characterized by; they fact that; the tube is formed and. compressed on. a permeable. mandrel, subject. internally to an action of suction, while the sa-id mandrel rotates within a trough orchannel'containing.thepaste;y the channel; being: subjected; to` a. periodical motion; noti parallel.. tothe; axis of the tuber..

The new apparatus for carrying outthisprocfl ess is characterised by a permeable mandrel, means for producing a vacuum within. thismanfdrei, a channel containing this mandrel, means forii'mpartng aV periodical motionto this chan.- nel along a direction which is. not that. of the axis of the tube and `means to cause the mandrel to rotate.

The new process and the new apparatus are hereinbel'ow described and `thereafter claimed.

By way of example there is described below an embodimentof the apparatus with reference, to the drawings appended in which:

Fig. l is a longitudinal section of the apparatus along the line I-I of Fig. 2.`

Fig. 2 is a cross-section along the line II--II of Fig. 1.

Figs. 3 to 10 are diagrammatic representations of diierent positions of the channel with respect to the mandrel in two cases.

With reference to the: drawings, I. is the permeable mandrel, the end journalZ of which is rotatable in the support 3, the base of. whichis a slide which can travel along suitable guides in the framework 4.

At the other end. the mandrelhas ajournal 5 inserted in a bush. 6 rotatable on the support 'I which is fixed to the frame-work 4.

'The journal 5` is -slidable in. the bush. 5 and its end portion 8 is of square cross-section. andeno g gages in a square portion of the hole of the bush.

The bush 6 has a toothed rim which meshes with a pinion ID with shaft il driven by known means, forexample motor or reduction. gearing; therefore when the shaft II rotates, the mandrel i i also rotates;

The end journal 2V is bored* and has insidefita tube I2'with suction elbow I3'; tube andA elbow do not rotate and the tube is connected to a suc.- tion pump. Y

I4 is :a channel tted With the two walls I5, I.6;, the channel has two flanges. which improve lateral tightness. i

In the interiory of the. channel. there is hollowed out at one end a recess I8 which corre-V spends to the socket of thevtube to beproduced;

there is likewise a corresponding recess in` the Walls I5 and I6.

I9 and 20 aretwo platesxed: to the frameworkv and their internal distance isequal .to the. length of the channel and equal to the length of thel tube to be. made.v

The plate. I9. is apertured to allow the passage of. the mandrel; the plate 20j. is provided. withY ay hole which. allows thezpassage of the'iinished tube and in this case the socket of the tube.

n thi-s hole there is lodged a ring 2l which can easily be fixed and removed, the aperture of which is slightly greater than the diameter of the mandrel at this part.

The surface of the ring directed towards the interior of the channel is on the same plane as the internal surface of the plate.

22 are two tie rods which regulate the distance of the two plates in such a way that the channel can move between them without having any play in the direction of the axis of the mandrel.

23 are two ribs joined to each other and Jo1ned to the channel, they constitute the tail portion of the channel and have two holes 24 in which there are lodged two eccentrics 25 in phase with each other, and both keyed on the shaft 2S rotatable on the supports 21 and driven by the pulley 28 which takes its movement from a motor, for example by means of a belt. L

In the lower part of the tail there is a pivot 29 which carries a lever 36 which, at the other end, is pivoted by means of a pin 3| to another lever 32 connected by fulcrum pin at 33 to two lugs 34 projecting from the framework 4. 'Ihe lever 32 is held in position by a spring 35 wh1ch thrusts it against the frame and by a screw 36 the female screw of which is cut in the lever 32 1tself. One end of the screw rests against the framework and the other end carries a handwheel 31 by rotating which it is possible to approach the lever 32 towards or make it recede from the framework. Consequently, by regulating this handwheel it is possible to displace the pin 3 I, the lever 36 and the pivot 29.

In other words, the tail of the channel w1ll be displaced and consequently the channel itself will be shifted in the opposite direction.

It is therefore possible with this device to vary transversely the position of the channel relatively to the mandrel and this displacement can be effected both when the apparatus is stopped and when it is in motion.

The adjustable spring 35 will elastically oppose the forces which might tend to make the lever recedefrom the framework. By rotating the shaft 26, the result is obtained that the pivot 29 will shift periodically along an arc of a circle having as its centre the joint 3l, while eachpoint of the channel will describe periodically a path the form of which depends on the cynematic characteristics of the operating device.

With reference to Figures 3 to 6 the axis of rotation of the mandrel, the axis of the shaft 26 which carries the excentric and the axis 29 of the lower pivot are in the same straight line and the internal curvature of the channel I4 is such that in the three positions of Figs. 3, 4, 5, the minimum distance of the channel from the mandrel is constant and equivalent to the thickness ofthe nished tube 38.

If on the other hand vthe pivot 29 is shifted to the left as in Figs. 6 to 10 the consequence will be that there will be the minimum distance ofthe channel from the mandrel in the case of Fig. 6.

, In any case the velocity of the point of the channel which is nearest to the mandrel must not be less than the velocity which` said point would have if .it were integral with the mandrel, otherwise the paste would be detached from the mandrel.

The example illustrated represents one of the forms of apparatus which allow of carrying out the process; Nevertheless its details may be varied without going beyond the scope of the present in' vention. Y

For example, it is possible by known means to vary the excentricity of the excentric 25 and this variation can even take place during the operation of the apparatus, or else the supports 21 can be mounted on slides so as to allow of regulating their position horizontally or vertically, for example, the actual movement of the channel can be replaced by any other movement provided it is not directed along the axis of the tube, and according to the paste employed in the cynematic characteristics of the movement of the canal must be suitably calculated. The screw 36 can be replaced by another apparatus which allows of causing the lever 32 to recede from the frame.

Or again, the entire device 30, 3l, 32, 33, 34, 35, 36, 31 may beapplied on the opposite part of the framework. The spring 35 may be replaced by another shock absorber, pneumatic, hydraulic or mechanical.

Means may also be provided for balancing the masses in alternate motion and in particular there may be combined on the same framework two devices acting on two mandrels so that the masses in alternating motion of one apparatus act in the opposed phase with the masses in alternating motion of the other apparatus, so that they can balance each other. The joint or articulation 29 can be formed by an elastic material and the pin 3| can be fixed directly to the framework. In the same way the slide 3 can be actuated by any of the known means, whether pneumatic, mechanical or hydraulic. The movement of the channel may be likewise not always at right angles to the axis of the mandrel I but could be guided in such manner as likewise to have a component parallel to the said axis.

In order to proceed to manufacture the tube the following course may be adopted: into the channel as described and as shown in Fig. 1 there is poured the whole of the paste previously prepared and intended for the manufacture of the tube, and the paste will occupy the whole of the free space between the mandrel and the channel.

The interior of the mandrel is put into communication with the suction pump, the mandrel itself is set rotating,'causing the shaft Il to rotate and the channel is put into periodic motion, causing the shaft 26 to rotate.

If the quantity of paste put in is correctly proportioned, in a short time all the paste will be collected round the mandrel. On continuing the suction action, the rotation of the mandrel and the periodical motion of the channel a further compression of the tube will be obtained if that is considered desirable.

At this point the movement of the shafts I I and 26 is stopped, the suction action is interrupted, the ring 2l of the plate 20 is released, the slide 3 is made to move in such a way that the whole of the mandrel passes out of the aperture in the plate 26 and between the ends of the mandrel and the said plate a suicient space is produced to allow of removing the tube. The tube is slipped off by applying pressure on the ring 2|, and the said tube is supported by known means or else the mandrel is removed from the support 3, and setting it vertizsillly the tube is slipped off by means of the ring According to the paste used -for the manufacture of the tube and according to the particulars to which the tube is to correspond it will be possible and in some cases desirable to adopt some of the measures indicated below.

As regards feeding the paste into the channel, for example, one of the following methods may beadopted A v Ai Thel paste required for thei manufacture-ion the tube-may be poured entirely: into the :channelcontaining the mandrel before Jstarting:l the mart?-Y ufacture.- lTn-tl'iat case itinayfhappenthattle quantity" of theA paste-poured ini islin'` itse'lnsuii-V cient in order that theimandrel; when. rn'a'n'ufa'cA ture is begun, shall rotatecompletelyJ immersed in the' paste. When that does.. nothappen', the paste mayv be made more moist so that the :man` drelfislcompletelyl immersed, inbrder. that manufacture shall start simultaneouslyatevery-point of .th'e' mandrel B;. Or else..- the: paste. can be partly poured. in before starting: manufacture, they remaining paste being addedduring manufacture; butJ always .vproceeding in such manner vthat at thefend `of each cycle of the periodical motion of the channel there shall. still. remain. in the: channel a` certain quantity of paste which has not yet adhered. to themandrel. The paste. poured in beforebeginning manufacture may be different from the paste. poured in subsequeently and in the particular. case of. pastes formed of cement and. breit. mayv be richer in bre or have stronger and longer fibers than the paste poured in subsequently. In that case the resulting tube will be at once economical and"`specially suitable'forwithstanding hydraulic pressure.

In the example shown in diagram in Figs. 3 to 6 the minimum distance of. the channel'from the mandrel is constant in the three positions shown in Figs. 3, 4, 5, so that the compression of the tube 38 will take placesubstantiallyin the same way in the three positions.

If, as has been said, the pin 29` is displaced to the left, the result will be that the distance be tween the channel and the mandrel will be least in the position shown in Fig. 7, a little greater in the position shown in Fig. 8 and still greater in the position shown in Fig. 9.

In other words, it will be in the position shown in Fig. 'l that the maximum pressure is'exerted.

Proceeding to manufacture the tube with the apparatus under these conditions, if the quantity of paste poured in is slightly excessive, what will happen is that when the paste is about to be adherent in its entirety on the mandrel, each time the channel is in the position shown in Fig. '7 the bottom pin of the tail Will tend to shift to the right.

The spring 35 (Fig. 2) will then intervene, elastically opposing this movement.

By rightly adjusting the spring 35 the required compression of the tube will be obtained and this compression will be constant even if the quantity of paste used is in excess relatively to the quantity theoretically required in order to produce a given thickness.

By maintaining the pivot of the tail always displaced to the left and suitably regulating the screw 36 by means of the handwheel 31, it will be possible to vary the thickness of the tube even during manufacture.

It is also possible with the machine under these conditions to compress any tube wound round a permeable mandrel and in this case the compression will be obtained by duly adjusting the spring Se so that the tail pivot recedes gradually from the straight line joining the axis of the mandrel with the axis of the shaft carrying the excentrics. Or again the compression may be 0btained by increasing during operation the excentricity of the excentric 25. Or again the compression may be obtained by suitably displacing lll the supports-211; In certain casesitwill a'lsof'be desirable to effect the for-mation'.'ofi the tube-inl an apparatus,v to remove the mandrel clothed with the tube thus. formed and;L to-mount ilt on-v another apparatus'inforder to-complete its` com pression; the speed offrotation ofthe mandrel an'df the characteristic o'f the:Y periodical movementv of' the' channel may beithe sameV ordiiTere'nt-'inf the" two machines usedaslabove inthe` manufacture off the same tube. In each case tliepastelhayibeiof any kind. By way o'fl example there may bey mentioneda paste'of cement and nbirouszmat'erial, .for exampleasbestcs, .butit iscbvi'ous' thattire vkproc-- ess-is applicablelikewise withlv other paste'ssuchl as will allow of ar hardening o'f thehollow'i body. after'itsformation'.`

It is'.V also possible tol arrange. a. reinforcement on the mandrel before applibationcf: theipasta. for example'metallic',` in spiral orcagei form having.. an internal diameter' greater.- than the m'an drel and of course an external: diameter" less than; the external diameter of the ytubeto be con-Y structed; by the. process described above: the-.reif inforcement is satisfactorily centred.

.Havingnow particularly described andv ascertained the. naturefof my said'- invention, and in' what manner the sameis tovbe performed,.I declare that what; L claim is:

1. Process for the manufacturev and/ theA com-- pression.- of/ tubes: from-.pastes capable `of hardening, thereby characterisedthat the tube is formedand compressedv on a permeable mandrel subuiected internally to a suction action While then said mandrel-rotates: inthe-interior of, achannel containing the paste. by subjecting saidlchannel tota periodical motiony in adirection.-` not parallel to the axis of the tube, the tubes thus produced being successively taken off.

2. Process according to the preceding claim, characterised by the fact that the whole of the paste required for the manufacture of the tube is poured into the channel containing the mandrel before beginning the manufacture of the tube.

3. Process according to claim 1, characterised by the fact that part of the paste is poured into the channel during the formation of the tube, pouring during a complete cycle of motion of the channel a quantity of paste greater than that which has been made to adhere to the mandrel during the said cycle.

4. Process according to claim 1, characterised by the fact that different qualities of paste vare successively poured into the channel partly during formation of the tube.

5. Process according to claim 1, characterised by the fact that before beginning the rotation of the mandrel a sufficient quantity of paste to submerge the mandrel completely is put into the channel.

6. Process according to claim 1, characterised by the fact that the path described by each point of the internal surface of the channel is stationary relatively to the position of the mandrel.

7. Process according to claim 1, characterised by the fact that the path which each point of the channel periodically described is, during the formation and/or the compression of the tube, displaced relatively to the mandrel in a plane perpendicular to the mandrel.

8. Process according to claim l, characterised in that the velocity of each point of the internal surface of the channel when that point attains its minimum distance from the mandrel is directed in the same direction as that which the said point would have at that moment if it were integral with the mandrel.

`9. Process according to claim 1, characterised by the fact that the velocity of each point of the internal surface of the channel when the said point attains its minimum distance from the mandrel is directed in the same direction as, and is greater than, that which the said point would have at the moment if it were integral with the mandrel.

10. Process according to claim 1, characterised by the fact that the suction action, the rotation of the mandrel and the periodical motion of the channel are continued even after all the paste has been applied to the mandrel.

11. Process according to claim l. characterised by the fact that the paste consists of cement and fibrous material.

12. Process according to claim 1, characterised by the fact that before pouring the paste into the channel there is arranged on the mandrel a metal reinforcement of a diameter greater than the diameter of the mandrel.

13. Apparatus for the manufacture and the compression of tubes from pastes capable of hardening, according to the process claimed in 1 to 12, characterized by a permeable mandrel, means for causing the mandrel to rotate and means for producing a vacuum in the interior of this mandrel, a channel which contains this mandrel, means for causing this channel to `move periodically not parallel to the axis of the mandrel.

14. Apparatus according to claim 13, characaround an axis parallel to the axis of the mandrel and on at least one other pivot having its axis parallel to the said two axes and situate in their plane beneath the rst pivot above mentioned and free to move in the said plane perpendicularly to the said axes.

l5. Apparatus according to claim 14, characterised by the fact that the internal transverse profile of the channel is an arc of a circle of a diameter greater than the external diameter of the tube to be formed.

16. Apparatus according to claim 14, characterised by the fact that the internal transverse profile of the channel is a semi-circle which is prolonged upwards along two tangents.

17. Apparatus according to claim 14, characterised by the fact that the channel is secured elastically in correspondence to the said second lower pvot.

18. Apparatus according to claim 14, characterised by the fact that the position of the second parallel pivot is displaceable perpendicularly to the said plane.

19. Apparatus according to claim 14, characterized by the fact that the excentricity of the said rst pivot is adjustable.

PINO SALVANESCHI.

Name Date Lemont et al. Apr. 9, 1946 Number 

